Art of carroting fur



Patented Feb. 16, 1937 UNITED STATES Aa'r F oAaaoTmG in Jack D.SartakoiLfilmhurst, N. Y.

No Drawing. Application August 11, 1936, Serial No. 95,424

6 Claims.

This invention relates to the art of carroting fur and like fibre. Thesaid fur or fibre may be used for a wide variety of purposes in the artsand the raw material may be the natural fur of rabbits, hares, nutria,muskrat or beaver or .any

other suitable animal fibre, but, for the purposeof illustration, theinvention is hereinafter described. as applied to the treatment ofrabbit fur for the making of felt hats.

10 Hitherto, almost all fur used in the manufacture of felt hats hasbeen treated with mercury nitrate, usually in the presence of freenitric acid and mostly with the further addition of hydrogen peroxide.The purpose of this treatment is to prepare the fur for felting.

It is, however, well recognized by the initiate that the use of mercury,in this connection is undesirable and, in fact, dangerous to workmenengaged in the preparation of fur for felting and the subsequent feltingthereof. Some of the mercury compounds produced are practicallyinsoluble in water and tend to remain in the fur with the consequentthreat of mercury poisoning, sometimes manifesting itself as mercuryeczema or mercury St. Vitusdance. In the presence of perspiration or theheat of the body, such mercury compounds may also have a detrimentaleffect upon the wearer. Hydrogen peroxide, heretofore used inconjunction with processes of the character under consideration, isdangerous to the healthof workmen engaged in the carroting operation andis undesirable.

In the form of the invention herein disclosed in some detail, neithermercury nor hydrogen peroxide is employed. In fact, the presentinvention provides for the complete elimination of mercury or hydrogenperoxide, or both, in the carroting operation.

To attain these and other ends the fur is herein 4o disclosed as treatedwith an acid solution of a salt of a per acid, such, for example, aspotassium or a other metal permanganate with a strong mineral acid suchas nitric acid. The solutions herein described further provide acarroting solution which is easily washed out during the feltingoperations,

so as to leave practically no trace of the carroting contrary, if toomuch acid is used, .the fur becomes a burned and deteriorated to suchextent as to render it commercially worthless. Betweenthese two extremesthere is an optimum zone wherein I have been able to carrot accordingtothe present invention with extraordinarily satisfactory results. Withinthis zone there is sufilcient acid employed to completely react all ofthe salt pres- 5 eat, plus an excess of acid. At the same time the acidused is less than that which will produce the burning to which I havereferred.

When furs were carroted according to the present invention with a.suitable composition 1 comprising nitric acid and potassiumpermanganate, it was found that, when the solution was first applied tothe fur, the fur had a violet color, which changed to a deep chocolate.The fur was kept wet while the action proceeded and 15 within a eriodgenerally between 12 to 72 hours, depending upon the strength of thepermanganate solution, the color disappeared entirely signifying thatthe reactions were completed and the carroting operation was concluded.The furs were 20 then dried to room temperature and were ready to beremoved from the skins and felted.

One advantage of the present invention, when operating within thisoptimum zone, is that it is unnecessary to heat artificially thecarroted fur,

' operation and it was by following this common procedure that saidoptimum zone was determined. Solutions prepared in accordance with thepresent invention were, in eachcase, spread upon the fur in-the usualmanner of carroting, and the furs dried at room temperature in aconventional way before starting and sizing. In conformance with usage,fur was started wet five rounds by machine and then sized wet five 4founds by hand and the resulting shrinkage was noted. To enable theshrinkage to be accurately ascertained, about seven and one-half gramsof fur were blown on to a flat, perforated disk to produce a bat ofabout 10" in diameter. The re- 4 suiting furbat or disk was thereuponsubjected to conventional starting and sizing steps referred to. andthen measured to ascertainthe shrinkage. This procedure was carried outwith widely varying carroting solutions differing from one an- 5 otherin graduated percentages 'ofpermanganates and other per salts-andnitric, sulphuric and other acids. The results obtained were such as toclearly demonstrate the fact that the use of insuflicient acid in the.solutions makes it impossi- 55 v ble to obtain a satisfactory commercialcarrot while the use of too much acid in the solutions producesdeterioration or burning of the fur. These tests further demonstratedthat betweenv these extremes for each fur bat, there was a point where adefinite relationship of acid to the per salt produced the bestshrinkage.

It is herein considered unnecessary to elucidate all of said tests, butthe following will be given by way of example to indicate the characterof the results obtainable according to the present invention.

Example 1.Clipped white French rabbit fur was carroted with a solutioncarrying 12 per cent of nitric acid and 2 per cent of potassiumpermanganate. After drying, the fur was started and sized as mentionedabove and a total shrinkage of '78 per cent in area was noted.

Testsmade with the same amount of potassium permanganate solutioncarrying either less acid or more acid produced less shrinkage. When thesame amount of potassium permanganate was used with lessthan 6 per centof the acid on this particular fur the shrinkage was not commercial andthe bat was loose and could not be properly felted. Also, when the acidcontent was raised to 19 per cent a similar unsatisfactory result wasobtained. The same optimum result of 78 per cent shrinkage in area wasobtained when the same fur was carroted with a solution carrying 10 percent of nitric acid and 3 per cent of potassium permanganate.

Similarly, no commercially useful result was obtained when less than 6per cent of acid was used with this percentage of potassiumpermanganate.

Example 2.-A'heavier sample of clipped white French rabbit fur, carrotedwith a solution carry-- ing 14 per cent nitric acid and 5 per cent ofpotassium permanganate, and treated in the above mentioned manner,showed a total shrinkage of '76 per cent in area.

Again, a decrease in acid percentage to 6 per cent, rendered the batuncommercial and, with .an increase of the acid to 1'1 per cent, theresultihg shrinkage was less satisfactory.

Example 3.A finer lot of clipped white French rabbit fur, carroted witha solution carrying 13 per cent nitric acid and 1 per cent potassiumpermanganate, yielded a total shrinkage of 75%.

In general it was found possible to use much stronger acid solutionswithout impairing their effect on carroting provided a' corespondinglystronger potassium permanganate content was used. These highlyconcentrated solutions have been found especially useful in treatingcertain coarse furs, but were also found to have no deleterious effecton other furs, despite their high acid contents, although the optimumshrinkage is somewhat reduced as shown by the following example:

Example 4.-Clipped white French rabbit fur was carroted with a solutioncontaining 6 per cent of potassium permanganate and 21 per cent ofnitric acid, yielding a. shrinkage of 75 per cent.

Example 5.-Clipped grey Australian rabbit fur carroted with a solutioncarrying 12 per cent nitric acid and 2 per cent of potassiumpermanganate yielded a total shrinkage of 76 per cent.

Other tests on grey Australian rabbit fur, parallel to the test of whiteFrench rabbit fur,

showed results comparable to that on the white French rabbit fur. In theforegoing examples, the nitric acid is computed as per cent nitric acid,although in actual tests a more dilute acid was used in properproportions to yield the percentage named.

I found that very satisfactory uniform results were obtained when Iapplied to, the fur an amount of carroting solution, of proper strength,about equal in weight to the weight of the pelt. A useful carrot could,however, be obtained by applying a greater weightof a more dilute orweaker solution.-

I also found that it is not absolutely essential to apply the acid andper salt mixed in the same solution, for I obtained satisfactory resultsby applying separate solutions carrying suitable proportions of the acidand salt.

It appeared that the shrinking operation de: pended for itsefiectiveness very largely upon the hydrogen ion content of thesolution, but the hydrogen ion content varied somewhat according to arather complicated curve with the different proportions of nitric acidused and with the different proportions of potassium permanganate used.

I found it possible to substitute sulphuric acid for the nitric acidwhen used in such proportions as to yield approximately the samehydrogen ion content, or to mix these acids. The products of reactionwith sulphuric acid, however, tended to injuriously affect the furunless the fur was subsequently treated, as with ammonia or otheralkali. A satisfactory procedure for treating sulphuric acid-treated furwas to expose the treated fur, in dried condition, to ammonia fumes orthe fumes of a suitable ammonium salt, either before or after thecarroted fur was cut from the skin, and either under pressure or afterevacuating the air therefrom. This neutralizing operation turned themanganese pink, but rendered it water-soluble so that it washed out inthe felting operation, with the result that the carrot of the presentinvention did not discolor the finished felt which retained the naturalcolor of the fur.

Instead of neutralizing the acids present with ammonia fumes or thefumes of a suitable ammovolatile acids which readily volatilize off,leaving the fur in a perfectly safe condition. Barium nitrate may alsobe used if sulphuric acid is present and also other soluble salts ofbarium may be employed depending on conditions.

According to another procedure, fur was treated with a solution ofpermanganate and sulphuric acid in the proper proportions used tocarrot, but in a solution too weak to give a satisfactory carrot. Tocomplete the carroting the fur was treated, after the permanganate hadcompletely reacted and the color had disappeared, with a solution of anoxygen-bearing barium salt, such as barium perchlorate or bariumchlorate, which precipitated the sulphuric acid contained in the fur asinsoluble barium salt and effected oxidation. This also prevented injuryto the fur by free sulphuric acid. The resulting reactions, when carriedout at room temperature, in addition to producing a satisfactory carrot,served to lighten the color of the fur. This last step may, if desired,be carried out under elevated temperatures to produce, in effect, ayellow" carrot.

With regard to all the methods of this invention, as hereinbeforedescribed, it is entirely feasible to effect the whole or part of thecarroting operations under elevated temperatures in order to obtain thecommercial advantages of yellow" carroting, such, for example, asspeeding up production, although, as previously stated, satisfactoryresults are obtained without the application of artificial heat.

As hereinbefore stated, the present invention provides for a completeelimination of mercury or hydrogen peroxide or both in the carrotingoperation. It is, however, possible to replace a part of the per saltwith the mercury nitrate or other mercury salt heretofore used to carrotfur or to add to the composition of this invention prising 2-3 per centpermanganate and 10-12 per cent nitric acid will ordinarily givesatisfactory results, but it will be understood that the process is onefor dealing with a large class of furs, each one presenting its specialproblem, and it is'obviously impossible to specify the precise treatmentwhich would be most successful and economical in each case.Consequently, preliminary tests must be made to determine the exactamount-of acid and salt to be used to obtain the best results for thepurposes in hand on each particular fur.

The foregoing description of this invention is 7 clearly suflicientlydefinite to guide those skilled in the art to its successfulapplication. The examples which have been given and which specifyproportions or percentages are to be understood as examples only and arenot given with the intent of limiting the invention, the scope of whichis commensurate with the appended claims.

Having thus described in detail certain embodiments of the invention,what I claim as new and desire to secure by Letters Patent is:

1. The process of carroting fur-which includes treating the fur with asolution containing permanganate and an acid selected from the groupconsisting of nitric and sulphuric, said acid being in excess of thatwhich will completely react the permanganate into a substantiallycolorless compound on the hit upon completion of the reacshrinkage butinsuflicien't to burn the fur.

' and the permanganate and acid being present in proportions sufficientto cause substantial shrink: age but insuflicient to burn the fur, andmaintaining the wet fur at room temperature until the reaction iscompleted. 7

-3. The process of carroting fur which includes treating the fur with asolution containing permanganate and nitric acid. said acid being inexcess of that which will completely react the permanganate into asubstantially colorless compound on the fur upon completion of thereaction, and the permanganate and acid being present in proportionssuflicient to cause substantial shrinkage but insuflicient to burn thefur.

4. The process of carroting fur which includes wetting the fur with asolution carrying an acid selected from the group consisting of nitricand sulphuric, and potassium permanganate, said acid being in excess ofthat which will completely react the permanganate into a substantiallycolorless compound on the fur upon completion of the reaction, and saidsolution having a hydrogen ion content equivalent to that of thereaction product of approximately 10-12 per cent of nitric acid and 2-3per cent of potassium permanganate.

5. The process or carroting fur which includes treating the fur with asolution containing permanganate and sulphuric acid, said acid being inexcess of that which will completely react the permanganate into asubstantially colorless compound on the fur upon completion of thereaction and the permanganate and acid being present in proportionssufilci'ent to cause substantial shrinkage but insuflicient to burn thefur, and thereafteriurther treating the wet fur with a barium salt toreact with the sulphuric acid to produce a volatile acid.

6. The process of carroting fur which includes treating the fur with asolution containing permanganate and sulphuric acid, said acid being inexcess of that which will completely react the permanganate into asubstantially colorless compound on the fur upon completion ot'thereaction,

and the permanganate and acid being present in after treating the furwith an oxygen-yielding barium salt to complete the carroting.

JACK n. sum-axons.

